JP5831344B2 - Aluminum alloy having excellent rigidity and manufacturing method thereof - Google Patents
Aluminum alloy having excellent rigidity and manufacturing method thereof Download PDFInfo
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Description
本発明は、剛性に優れたアルミニウム合金及びその製造方法に関する。 The present invention relates to an aluminum alloy having excellent rigidity and a method for producing the same.
従来より、自動車等の各種輸送機器の部材としては鉄鋼材料が使用されている。しかしながら、鉄鋼材料は重量が嵩むために、省エネ化の観点等から素材の軽量化が望まれている。今後、益々軽量化が図られることになるため、鉄鋼材料並みの機械的強度と剛性を有する軽量な素材の開発が急務となっている。
他方、鋳造性に優れながら機械的強度の高いアルミニウム合金の開発がされてきており、このような特性を持つアルミニウム合金の各種輸送機器の部材への適用により、これらの部材の大幅な軽量化が図られてきている。
Conventionally, steel materials have been used as members of various transportation equipment such as automobiles. However, since the steel material is heavy, it is desired to reduce the weight of the material from the viewpoint of energy saving. In the future, the weight will be further reduced, so it is urgent to develop a lightweight material having mechanical strength and rigidity comparable to steel materials.
On the other hand, aluminum alloys having excellent castability and high mechanical strength have been developed, and the application of aluminum alloys having such characteristics to various transport equipment members has significantly reduced the weight of these members. It has been illustrated.
例えば、JIS規格のAC4C合金或いはAC4CH合金は、Al‐7%Si‐0.35Mgなる化学組成を基本とする、時効硬化型の合金であるが、優れた鋳造性と機械的強度とを兼ね備えたアルミニウム合金として自動車等の各種輸送機器の部材に用いられている。しかしながら、これらの合金を輸送機器の部材として使用する際、使用する箇所によっては剛性が足りないケースがある。
このため、アルミニウム合金の剛性を向上させる方法が、従来より提案されている。アルミニウム合金の剛性を向上させる、すなわち弾性率をより高くする方策のひとつが、より剛性の高い物質を分散材としての、分散材との複合化である。
For example, JIS standard AC4C alloy or AC4CH alloy is an age-hardening type alloy based on the chemical composition of Al-7% Si-0.35Mg, but it has excellent castability and mechanical strength. It is used as an alloy for members of various transportation equipment such as automobiles. However, when these alloys are used as members of transportation equipment, there are cases where the rigidity is insufficient depending on the location of use.
For this reason, a method for improving the rigidity of the aluminum alloy has been conventionally proposed. One of the measures to improve the rigidity of the aluminum alloy, that is, to increase the elastic modulus, is to combine the material having higher rigidity with the dispersing material as the dispersing material.
例えば、特許文献１は、Al2O3、SiC、SiO2、B4C、BN、TiB2、TiCの粒子、ウィスカまたは繊維を分散材としての複合化を提案している。また特許文献２、３、４は、それぞれTiN、TiC、AlB2を分散材としての複合化を提案している。
さらに特許文献５は、高剛性の繊維、ウィスカなどの分散材を含む被覆部を部材の一部に設けることを提案している。
TiB2は剛性が高く、アルミニウム合金との濡れ性にも優れるため、アルミニウム合金の剛性を高くする目的に対して好適である。例えば、特許文献６は、剛性の高いTiB2をアルミニウム合金中に分散させ、複合化することを提案している。また特許文献７は、高剛性の炭素繊維をTiB2で被覆したうえでアルミニウム合金中に分散、複合化することを提案している。
For example, Patent Document 1 proposes composite using Al 2 O 3 , SiC, SiO 2 , B 4 C, BN, TiB 2 , TiC particles, whiskers, or fibers as a dispersing material. Patent Documents 2, 3, and 4 propose compounding using TiN, TiC, and AlB 2 as dispersion materials, respectively.
Furthermore, patent document 5 has proposed providing the coating | coated part containing dispersion materials, such as a highly rigid fiber and a whisker, in a part of member.
Since TiB 2 has high rigidity and excellent wettability with an aluminum alloy, it is suitable for the purpose of increasing the rigidity of the aluminum alloy. For example, Patent Document 6 proposes that TiB 2 having high rigidity is dispersed in an aluminum alloy to be compounded. The Patent Document 7, dispersed in the aluminum alloy in terms of coated carbon fibers of a high rigidity TiB 2, it is proposed to composite.
しかしながら、前記各文献で提案されているアルミニウム合金について細かく検討してみると、アルミニウム合金の剛性を向上させる目的で、より剛性の高い物質を分散材として複合化させた場合、TiB2のように、アルミニウム合金との濡れ性が高い物質であっても、マトリックスであるアルミニウム合金との密度差が大きいことから、凝集し偏在してしまう場合が多々見られた。
このような分散材の凝集は、アルミニウム合金の特性が均一化しない原因となり、ひいてはアルミニウム合金を薄肉化し辛くなる原因となって、軽量化が達成されないという問題がある。また、アルミニウム合金への多量の分散材による複合化は、アルミニウム合金を鋳造する際に溶湯の流動性を低下させるために、重力鋳造では湯回り不良が多く発生し外観不良となってしまうほか、鋳巣の発生にともなって、機械的特性並びに剛性を低下させる要因ともなる。
However, when the aluminum alloy proposed in each of the above documents is examined in detail, when a material with higher rigidity is combined as a dispersing material for the purpose of improving the rigidity of the aluminum alloy, as in TiB 2 Even if the material has high wettability with the aluminum alloy, the density difference from the aluminum alloy which is a matrix is large, so that the material is often agglomerated and unevenly distributed.
Such agglomeration of the dispersion material causes the characteristics of the aluminum alloy not to be uniform, and thus causes the aluminum alloy to become thin and difficult to be formed, resulting in a problem that weight reduction cannot be achieved. In addition, the compounding with a large amount of dispersion material into the aluminum alloy reduces the fluidity of the molten metal when casting the aluminum alloy. Accompanying the occurrence of the cast hole, it also becomes a factor of lowering mechanical properties and rigidity.
また、剛性が高く、アルミニウム合金との濡れ性にも優れるTiB2をアルミニウム合金中に生成させようとして、アルミニウム合金溶湯にTiやBを添加した場合、TiB2以外の粗大な化合物（Al3TiやAlB2）が晶出し、そのような粗大化合物がアルミニウム合金の機械的特性の低下の原因となることがあること、及び、TiB2は融点が高いために通常の溶解温度では固体として存在し、多量のTiB2化合物を添加する場合は溶湯流動性の問題が生じることが判った。
本発明は、このような課題を解決するために案出されたものであり、剛性が高く、アルミニウム合金との濡れ性にも優れるTiB2を分散材として複合化させるにあたって分散材をアルミニウム合金の部材全体にわたって均一に分散させるとともに、Al3Ti化合物などの粗大防止することにより、剛性が高く、部材全体にわたって特性の均一なアルミニウム合金及びその製造方法を提供することを目的とする。
In addition, when Ti or B is added to the molten aluminum alloy to produce TiB 2 with high rigidity and excellent wettability with the aluminum alloy, a coarse compound other than TiB 2 (Al 3 Ti And AlB 2 ) crystallize, such coarse compounds may cause the mechanical properties of aluminum alloys to deteriorate, and TiB 2 exists as a solid at normal melting temperatures due to its high melting point. It has been found that when a large amount of TiB 2 compound is added, there is a problem of melt fluidity.
The present invention has been devised to solve such a problem, and in dispersing TiB 2 having high rigidity and excellent wettability with an aluminum alloy as a dispersion material, the dispersion material is made of an aluminum alloy. An object of the present invention is to provide an aluminum alloy having high rigidity and uniform characteristics over the entire member and a method for producing the same by dispersing the entire member uniformly and preventing coarseness of the Al 3 Ti compound and the like.
本発明の剛性に優れたアルミニウム合金は、その目的を達成するためにSi：5〜10質量％、Mg：0.1〜0.5質量％、Ti：1〜5質量％、B：0.3〜2質量％、および残部：Alと不可避不純物からなる化学組成と、TiB2の凝集体が1mm3当たり5個以下、Al3Tiの最大サイズが50μm以下、鋳巣の面積率が5％以下である金属組織を備えていることを特徴とする。
本発明のアルミニウム合金は、剛性を向上させるために、0.2質量％以上3%以下のMn、0.2質量％以上3%以下のCrをのうちの１種類以上を更に含むことができる。
本発明の剛性に優れたアルミニウム合金は、上記化学組成を有するアルミニウム合金溶湯に、液相線温度以上かつ液相線から100℃以内の温度範囲で、20〜27kHz，出力2kW以上の超音波振動を30秒以上照射し、照射終了後180秒以内に20℃／s以上の冷却速度で加圧鋳造を行うことにより得られる。
In order to achieve the object of the aluminum alloy having excellent rigidity of the present invention, Si: 5 to 10% by mass, Mg: 0.1 to 0.5% by mass, Ti: 1 to 5% by mass, B: 0.3 to 2% by mass, And the balance: a chemical composition consisting of Al and inevitable impurities, a metal structure with an aggregate of TiB 2 of 5 or less per mm 3, a maximum size of Al 3 Ti of 50 μm or less, and an area ratio of the casting cavity of 5% or less It is characterized by having.
In order to improve rigidity, the aluminum alloy of the present invention may further include one or more of 0.2% by mass to 3% Mn and 0.2% by mass to 3% Cr.
The aluminum alloy having excellent rigidity according to the present invention is an ultrasonic vibration of 20 to 27 kHz and an output of 2 kW or more in a temperature range of not less than the liquidus temperature and within 100 ° C. from the liquidus line to the molten aluminum alloy having the above chemical composition. Can be obtained by performing pressure casting at a cooling rate of 20 ° C./s or more within 180 seconds after irradiation.
前記加圧鋳造は、好ましくはダイカスト鋳造法であるが、さらに好ましくは半凝固ダイカスト鋳造法である。
また上記方法により得られた鋳塊に500℃〜535℃で6〜8時間加熱する溶体化処理を施した後、100℃以下までを20℃／s以上の冷却速度で冷却し、その後に150℃〜300℃で1〜10時間加熱する時効硬化処理を施すことが好ましい。
The pressure casting is preferably a die casting method, more preferably a semi-solid die casting method.
In addition, the ingot obtained by the above method was subjected to a solution treatment of heating at 500 ° C. to 535 ° C. for 6 to 8 hours, and then cooled to 100 ° C. or less at a cooling rate of 20 ° C./s or more. It is preferable to perform an age hardening treatment in which heating is carried out at a temperature of from C to 300 C for 1 to 10 hours.
本発明によれば、超音波照射を行うことにより、晶出したTiB2をアルミニウム合金部材全体にわたって均一に分散させることができるため、部材全体にわたって均一に剛性を向上させことができ、さらに粗大な化合物の晶出を抑えることで、優れた機械的特性を発揮することができる。さらに、ダイカスト鋳造法または半凝固ダイカスト鋳造法により鋳造を行うことでその方法の一つの特長である加圧力によって、鋳巣を低減させることができるため、鋳巣の存在による機械的特性並びに剛性の低下がない。
このため、自動車等の各種輸送機器の部材、特に薄肉化による軽量化及び剛性が必要とされる自動車用ナックルアームやホイール、内燃機関のシリンダーヘッドに好適であるほか、プラスチックの超音波加工用の振動子などの素材としても利用可能である。
According to the present invention, by performing ultrasonic irradiation, the crystallized TiB 2 can be uniformly dispersed over the entire aluminum alloy member, so that the rigidity can be improved uniformly over the entire member, and the coarser By suppressing the crystallization of the compound, excellent mechanical properties can be exhibited. Furthermore, since casting can be reduced by applying pressure, which is one of the features of the casting, by casting by the die casting method or semi-solid die casting method, the mechanical characteristics and rigidity of the casting cavity are reduced. There is no decline.
For this reason, it is suitable for parts of various transport equipment such as automobiles, especially for knuckle arms and wheels for automobiles that require weight reduction and rigidity due to thinning, cylinder heads for internal combustion engines, and for ultrasonic processing of plastics. It can also be used as a material for vibrators.
本発明者等は、自動車等各種輸送機器の部材に好適に利用できるアルミニウム合金材として、機械的強度が高く、鋳造用合金として鋳造性に優れるものとして、従来から各種輸送機器に利用されているJIS規格のAC4C合金やAC4CH合金の高剛性化策について検討を重ねてきた。
その過程で、アルミニウム合金との濡れ性にも優れるTiB2をアルミニウム合金中に均一に分散させることができれば、剛性を向上させることができて自動車用ナックルアームやホイール、内燃機関のシリンダーヘッドに好適なものとすることができることを見出した。
The present inventors have been conventionally used in various transportation equipment as an aluminum alloy material that can be suitably used for members of various transportation equipment such as automobiles, as having high mechanical strength and excellent castability as a casting alloy. We have been studying measures to increase the rigidity of JIS standard AC4C alloy and AC4CH alloy.
In the process, if TiB 2 that has excellent wettability with aluminum alloy can be uniformly dispersed in the aluminum alloy, the rigidity can be improved and it is suitable for knuckle arms and wheels for automobiles and cylinder heads of internal combustion engines. I found out that it can be.
さらに鋭意検討することにより、アルミニウム合金の鋳造に際して、超音波照射を行うことにより、TiB2をアルミニウム合金部材全体にわたって均一に分散させて含有させるとともに、粗大な化合物の晶出を抑えることができ、またダイカスト鋳造法または半凝固ダイカスト鋳造法の採用との組合せにより、鋳巣を低減させることができることを見出し、本発明に到ったのである。
以下にその詳細を説明する。
By further intensive study, when casting aluminum alloy, by irradiating with ultrasonic waves, TiB 2 can be uniformly dispersed throughout the aluminum alloy member and crystallization of coarse compounds can be suppressed, Further, the present inventors have found that the cast hole can be reduced by the combination with the die casting method or the semi-solid die casting method, and have reached the present invention.
Details will be described below.
まず、本発明アルミニウム合金の化学組成について説明する。
＜必須成分＞
〔Si：5〜10質量%〕
Siは、剛性等の機械的性質の向上や、耐摩耗性、鋳造性を向上させる作用がある。本発明は、JIS規格のAC4C或いはAC4CHを基本とするものであるから、Si含有量は6.5〜7.5質量%の範囲が好ましいが、5〜10質量%の範囲であれば実施できる。Siが5質量％に満たないと、溶湯の流動性が十分でなく、複雑な形状や薄肉部を有するものを鋳造する場合には、成形性の観点から好ましくない。また、Si含有量が10質量%を超えると、延性が低下し、好ましくない。そこで、Si含有量は5〜10質量%の範囲とする。
First, the chemical composition of the aluminum alloy of the present invention will be described.
<Essential ingredients>
[Si: 5-10% by mass]
Si has the effect of improving mechanical properties such as rigidity, and improving wear resistance and castability. Since the present invention is based on JIS standard AC4C or AC4CH, the Si content is preferably in the range of 6.5 to 7.5% by mass, but can be implemented in the range of 5 to 10% by mass. If Si is less than 5% by mass, the fluidity of the molten metal is not sufficient, and it is not preferable from the viewpoint of moldability when casting a metal having a complicated shape or thin portion. On the other hand, when the Si content exceeds 10% by mass, the ductility is lowered, which is not preferable. Therefore, the Si content is in the range of 5 to 10% by mass.
〔Mg：0.1〜0.5質量%〕
Mgは溶体化状態において固溶強化によって機械的強度を向上させる作用があるほか、後述する時効硬化処理においては、SiとともにMg2Si化合物を形成して析出し、機械的強度をさらに向上させる作用がある。Mgも、本発明がJIS規格のAC4C及びAC4CHを基本とするものであるから、その好ましい含有量の範囲は0.25〜0.45質量%であるが、実施可能な範囲は0.1〜0.5質量%である。Mgが0.1質量%を下回ると前述の効果による機械的強度の向上の作用が不足するため、好ましくない。Mgが0.5質量%を超えると、Siとの反応により形成、析出するMg2Si化合物の量が増大し、延性が低下するため、好ましくない。また、特に超音波照射する際に、Mgの添加によってキャビテーション（微細な泡）が発生しやすくなるため、微細化効果を発揮する。この作用は0.1質量%以上の添加で顕著となるが、0.5質量%を超えると析出するMg2Siが多くなり、伸びが低下し鋳造性が低下する。そこでMgの添加量は0.1質量%〜0.5質量％の範囲とする。
[Mg: 0.1-0.5% by mass]
Mg has the effect of improving mechanical strength by solid solution strengthening in the solution state, and in the age hardening treatment described later, it forms and precipitates Mg 2 Si compound with Si, and further improves mechanical strength. There is. Since Mg is based on JIS standard AC4C and AC4CH, the preferred range of Mg is 0.25 to 0.45% by mass, but the feasible range is 0.1 to 0.5% by mass. If Mg is less than 0.1% by mass, the effect of improving the mechanical strength due to the above-described effect is insufficient, which is not preferable. If Mg exceeds 0.5% by mass, the amount of Mg 2 Si compound formed and precipitated by reaction with Si increases and ductility decreases, which is not preferable. In particular, when ultrasonic waves are applied, cavitation (fine bubbles) is likely to occur due to the addition of Mg. This effect becomes remarkable when 0.1% by mass or more is added, but when it exceeds 0.5% by mass, Mg 2 Si precipitated increases, elongation decreases, and castability deteriorates. Therefore, the amount of Mg added is in the range of 0.1% by mass to 0.5% by mass.
〔Ti：1〜5質量%及びB：0.3〜2質量%〕
TiとBは互いに結合してTiB2なる化合物を形成して剛性向上に大きく寄与する元素である。Ti量が1質量%に満たなかったり、B量が0.3質量％に満たなかったりすると、剛性を向上させるTiB2の生成量が少なくなってしまい、剛性向上効果が充分でない。逆にTi量が5質量%を超える程に多かったり、B量が2質量%を超える程に多かったりすると、TiB2は微粒子かつアルミニウムとの密度差が大きいことから、凝集、偏在して鋳造時に超音波を照射しても均一に分散させることができない。また、Tiの量が多くなると粗大な化合物Al3Tiが晶出するため機械的特性が低下し、B量が多くなると粗大な化合物AlB2が晶出するため機械的特性が低下してしまう。そこでTiの添加量は1〜5質量%、Bの添加量は0.3〜2質量%の範囲とする。
[Ti: 1-5% by mass and B: 0.3-2% by mass]
Ti and B are elements that bond to each other to form a compound of TiB 2 and greatly contribute to the improvement of rigidity. If the amount of Ti is less than 1% by mass or the amount of B is less than 0.3% by mass, the amount of TiB 2 that improves rigidity decreases, and the effect of improving rigidity is not sufficient. Conversely, if the amount of Ti exceeds 5% by mass or the amount of B exceeds 2% by mass, TiB 2 is agglomerated and unevenly distributed due to the large density difference between the fine particles and aluminum. Sometimes even ultrasonic waves cannot be uniformly dispersed. Further, when the amount of Ti increases, the coarse compound Al 3 Ti crystallizes, so that the mechanical characteristics deteriorate, and when the amount of B increases, the coarse compound AlB 2 crystallizes, and the mechanical characteristics deteriorate. Therefore, the addition amount of Ti is in the range of 1 to 5% by mass, and the addition amount of B is in the range of 0.3 to 2% by mass.
＜任意添加成分＞
剛性を向上させるために、ＭｎおよびＣｒの少なくとも一方を下記の範囲で必要に応じて任意に添加できる。
<Optional components>
In order to improve the rigidity, at least one of Mn and Cr can be arbitrarily added within the following range as necessary.
〔Mn：0.2〜3質量％〕
Mnは剛性向上に寄与するAlMn系，AlMnSi系晶出物を形成し、剛性を向上させる作用があり、必要に応じて含有させる。これらの晶出物は、アルミニウムとの濡れ性は良く、TiB2とアルミニウム合金の濡れ性にも影響を与えないため、TiB2添加による剛性向上を阻害することなく、さらなる剛性向上を達成できる。0.2質量％以下ではこのような効果が小さく、3質量％を超える程に多くなると、破壊の起点となるAlMn系，AlMnSi系晶出物が多くなってかえって、伸び等の機械的性質を低下させることになる。したがって、Mnの添加量は0.2質量％〜3質量％以下とする。
[Mn: 0.2-3 mass%]
Mn forms AlMn-based and AlMnSi-based crystallized substances that contribute to rigidity improvement, and has the effect of improving rigidity, and is contained as necessary. Since these crystallized materials have good wettability with aluminum and do not affect the wettability of TiB2 and aluminum alloy, further improvement in rigidity can be achieved without inhibiting the increase in rigidity due to the addition of TiB2. When the amount is less than 0.2% by mass, such an effect is small, and when the amount exceeds 3% by mass, the AlMn-based and AlMnSi-based crystallized substances that become the starting point of fracture increase, which reduces mechanical properties such as elongation. It will be. Therefore, the addition amount of Mn is 0.2 mass% to 3 mass% or less.
〔Cr：0.2〜3質量％〕
Crは剛性向上に寄与するAlCr系，AlCrSi系晶出物を形成し、剛性を向上させる作用があり、必要に応じて含有させる。これらの晶出物は、アルミニウムとの濡れ性は良く、TiB2とアルミニウム合金の濡れ性にも影響を与えないため、TiB2添加による剛性向上を阻害することなく、さらなる剛性向上を達成できる。0.2質量％以下ではこのような効果が少なく、3質量％を超える程に多くなると、破壊の起点となるAlCr系，AlCrSi系晶出物が多くなってかえって、伸び等の機械的性質を低下させることになる。したがって、Crの添加量は0.2質量％〜3質量％以下とする。
[Cr: 0.2-3 mass%]
Cr forms an AlCr-based or AlCrSi-based crystallized substance that contributes to the improvement of rigidity, and has the effect of improving the rigidity, and is contained if necessary. Since these crystallized materials have good wettability with aluminum and do not affect the wettability of TiB2 and aluminum alloy, further improvement in rigidity can be achieved without inhibiting the increase in rigidity due to the addition of TiB2. When the amount is less than 0.2% by mass, such an effect is small, and when the amount exceeds 3% by mass, the AlCr-based and AlCrSi-based crystallized substances that become the starting point of fracture increase, resulting in a decrease in mechanical properties such as elongation. It will be. Therefore, the amount of Cr added is 0.2 mass% to 3 mass% or less.
＜不可避不純物＞
不可避不純物としては、Ｆｅ、Ｃｕなどを挙げることができる。不可避不純物の含有量は、ＦｅおよびＣｕはそれぞれ０．３質量％未満、他の不可避不純物は、各元素０．０５質量％未満、合計０．３質量％未満であれば本発明を実施できる。
<Inevitable impurities>
Examples of inevitable impurities include Fe and Cu. The present invention can be carried out if the content of inevitable impurities is less than 0.3% by mass for Fe and Cu, and the other inevitable impurities are less than 0.05% by mass for each element, and the total is less than 0.3% by mass.
次に、本発明アルミニウム合金の金属組織について説明する。
〔TiB2の凝集体：1mm3当たり5個以下〕
TiB2の凝集体が多いと、靭性が低下する。そこで、本発明では、アルミニウム合金中のTiB2の凝集体は1mm3当たり5個以下とする。ところで、TiB2の凝集体は、平面写真では図２に示すようにリング状に観察されるが、立体的には外径50μm以上の球殻状の形状である凝集体のことをいう。なお図２に示すような平面写真での観察においては、球殻の切断面によっては、外径が50μm以下に観察されることもある。
後述するように、各元素を上記の組成範囲に調整したアルミニウム合金溶湯に、液相線温度以上かつ液相線温度から100℃以内の温度範囲の合金溶湯に所定条件で超音波照射することにより、TiB2の凝集体の生成を防ぐことができるとともに、TiB2を部材内に均一に分散することができる。
Next, the metal structure of the aluminum alloy of the present invention will be described.
[TiB 2 aggregates: 5 or less per 1 mm 3 ]
When there are many TiB 2 aggregates, toughness decreases. Therefore, in the present invention, the number of TiB 2 aggregates in the aluminum alloy is 5 or less per 1 mm 3 . By the way, the aggregate of TiB 2 is observed in a ring shape as shown in FIG. 2 in a plan view, but it means a three-dimensional aggregate having a spherical shell shape with an outer diameter of 50 μm or more. In observation with a plane photograph as shown in FIG. 2, the outer diameter may be observed to be 50 μm or less depending on the cut surface of the spherical shell.
As will be described later, by ultrasonically irradiating a molten aluminum alloy with each element adjusted to the above composition range to a molten alloy at a temperature range above the liquidus temperature and within 100 ° C from the liquidus temperature under predetermined conditions. In addition, the formation of TiB 2 aggregates can be prevented, and TiB 2 can be uniformly dispersed in the member.
〔粗大な化合物の最大サイズ：50μm以下〕
Tiを添加したＡＣ４Ｃ合金やＡＣ４ＣＨ合金では、化合物Al3Tiが晶出し、粗大化して機械的特性を低下させることがある。そこで、本発明合金では、機械的強度の低下を抑えるために、Al3Tiなどの化合物の大きさを50μm以下のサイズとする。
Al3Tiの粗大な化合物は図３に示すような針状に成長する。Al3Ti化合物は超音波振動を付与する温度域では既に晶出しているため、超音波キャビテーションによって粗大なAl3Ti化合物を分断することができると考えられる。後述するように、各元素を上記の組成範囲に調整したアルミニウム合金溶湯に、液相線温度以上かつ液相線温度から100℃以内の温度範囲の合金溶湯に所定条件で超音波照射することにより、Al3Tiなどの化合物の大きさを50μm以下のサイズにすることができる。
[Maximum size of coarse compound: 50 μm or less]
In an AC4C alloy or an AC4CH alloy to which Ti is added, the compound Al 3 Ti may crystallize and coarsen to deteriorate mechanical properties. Therefore, in the alloy of the present invention, the size of a compound such as Al 3 Ti is set to 50 μm or less in order to suppress a decrease in mechanical strength.
The coarse compound of Al 3 Ti grows in a needle shape as shown in FIG. Since Al 3 Ti compounds are already crystallized in the temperature range where ultrasonic vibration is applied, it is considered that coarse Al 3 Ti compounds can be divided by ultrasonic cavitation. As will be described later, by ultrasonically irradiating a molten aluminum alloy with each element adjusted to the above composition range to a molten alloy at a temperature range above the liquidus temperature and within 100 ° C from the liquidus temperature under predetermined conditions. The size of a compound such as Al 3 Ti can be reduced to 50 μm or less.
〔鋳巣の面積率：5％以下〕
アルミニウム合金鋳物材にあっては、鋳巣の存在は機械的強度や靭性を低減させる要因となる。そこで、本発明合金では、機械的強度や靭性の低下を抑えるために、鋳巣を面積率で5％以下にした。
TiB2を生成させたアルミニウム合金においては鋳巣が発生しやすくなるが、加圧鋳造を行うことで鋳巣を低減させることができる。
[Cavity area ratio: 5% or less]
In an aluminum alloy casting material, the presence of a casting hole causes a reduction in mechanical strength and toughness. Therefore, in the alloy of the present invention, in order to suppress a decrease in mechanical strength and toughness, the casting hole is made 5% or less in terms of area ratio.
In the aluminum alloy in which TiB 2 is generated, a void is likely to occur, but the void can be reduced by performing pressure casting.
続いて、本発明にアルミニウム合金の製造方法について説明する。
本発明方法では、上記の添加元素と不可避不純物からなる化学組成のアルミニウム合金溶湯に超音波振動を照射した後、加圧鋳造により鋳造を行っている。
用いる超音波処理用の装置としては、図１に示すような、超音波ジェネレータ1、振動子2、ホーン3と制御ユニットから構成されているものが好ましい。一例として、磁歪振動子を構成した超音波発生装置の操作原理を説明する。超音波ジェネレータ1により発生した交流強力電流を超音波振動子2に印加し、超音波振動子によって発生した超音波振動はネジ方式接続4を介してホーン3によってホーン先端に伝達し、先端からアルミニウム合金溶湯中に導入する。共振条件を保つために、共振周波数自動制御ユニット5を備えている。このユニットは、振動子に流れる電流値を周波数の関数として測定し、電流値が最大値を保持するように、周波数を自動調整するものである。
Then, the manufacturing method of an aluminum alloy is demonstrated to this invention.
In the method of the present invention, casting is performed by pressure casting after irradiating ultrasonic vibration to a molten aluminum alloy having a chemical composition composed of the above-described additive elements and inevitable impurities.
As the ultrasonic processing apparatus to be used, an apparatus including an ultrasonic generator 1, a vibrator 2, a horn 3 and a control unit as shown in FIG. 1 is preferable. As an example, the operation principle of an ultrasonic generator that constitutes a magnetostrictive vibrator will be described. The AC strong current generated by the ultrasonic generator 1 is applied to the ultrasonic vibrator 2, and the ultrasonic vibration generated by the ultrasonic vibrator is transmitted to the horn tip by the horn 3 via the screw connection 4 and from the tip to the aluminum. Introduce into molten alloy. In order to maintain the resonance condition, a resonance frequency automatic control unit 5 is provided. This unit measures the current value flowing through the vibrator as a function of frequency and automatically adjusts the frequency so that the current value maintains the maximum value.
この際に用いる超音波ホーンは、高耐熱性を有しアルミニウム合金溶湯中で超音波照射させてもエロージョンされ難い材料、例えばセラミックス材料、耐熱性の高い金属としてはNb‐Mo合金などを選択することができる。なお付与する振動としては振幅10〜70μm（p‐p）、周波数20〜27kHzで、アルミニウム合金溶湯1kg当たり出力2kW以上程度の超音波を付与することでTiB2の均一な分散化とAl3Tiなどの化合物の微細化を達成することができる。なお、AlMn系，AlMnSi系晶出物、AlCr系，AlCrSi系晶出物は針状ではなく塊状のため超音波照射による微細化効果は発揮されないと考えられる。ここで、p‐pはピーク‐to‐ピークであり、例えばサイン波の場合は最大値と最低値との差のことをさす。超音波振動が、振幅10〜70μm（p‐p）、周波数20〜27kHzの範囲を外れるとTiB2の均一な分散化とAl3Tiなどの化合物の微細化が達成できない。またアルミニウム合金溶湯1kg当たりの超音波振動の出力が2kW未満であると振動の出力が不足し、TiB2の均一な分散化とAl3Tiなどの化合物の微細化が達成できない。 The ultrasonic horn used at this time is selected from materials that have high heat resistance and are not easily eroded even when irradiated with ultrasonic waves in molten aluminum alloy, for example, ceramic materials, and Nb-Mo alloy as a metal with high heat resistance. be able to. Note the amplitude 10~70μm as vibration imparting (p-p), at a frequency 20～27KHz, uniform dispersion of TiB 2 by applying ultrasonic degree aluminum alloy melt 1kg per output 2kW or more and Al 3 Ti Refinement of a compound such as can be achieved. In addition, since the AlMn-based, AlMnSi-based crystallized product, AlCr-based, and AlCrSi-based crystallized product are not in the form of needles but in a lump shape, it is considered that the effect of refining by ultrasonic irradiation is not exhibited. Here, pp is a peak-to-peak, and refers to the difference between the maximum value and the minimum value in the case of a sine wave, for example. If the ultrasonic vibration is out of the range of amplitude 10 to 70 μm (pp) and frequency 20 to 27 kHz, uniform dispersion of TiB 2 and refinement of compounds such as Al 3 Ti cannot be achieved. In addition, if the output of ultrasonic vibration per 1 kg of molten aluminum alloy is less than 2 kW, the output of vibration is insufficient, and uniform dispersion of TiB 2 and refinement of compounds such as Al 3 Ti cannot be achieved.
各元素を上記の組成範囲に調整したアルミニウム合金溶湯に超音波振動を照射するが、超音波照射時の合金溶湯温度は液相線温度以上かつ液相線温度から100℃以内とし、超音波照射は30秒以上行う。
液相線温度以上で超音波照射を行うことで高い微細化効果を得られ、かつ液相線温度から100℃以内にすることで超音波照射終了から凝固までの時間を短縮することができる。
また、溶湯温度が高すぎると溶湯中のガス量が増え溶湯品質が低下したり、炉材、ホーンなどの寿命が低下したりする危険がある。したがって、超音波照射温度は液相線温度以上かつ液相線温度から100℃以内とする。
Irradiate ultrasonic vibration to the molten aluminum alloy with each element adjusted to the above composition range, but the molten alloy temperature at the time of ultrasonic irradiation should be higher than the liquidus temperature and within 100 ° C from the liquidus temperature. Do more than 30 seconds.
By performing ultrasonic irradiation above the liquidus temperature, a high micronization effect can be obtained, and by setting the temperature within the liquidus temperature to 100 ° C. or less, the time from the end of ultrasonic irradiation to solidification can be shortened.
Further, if the molten metal temperature is too high, there is a risk that the amount of gas in the molten metal increases and the quality of the molten metal decreases and the life of the furnace material, horn, etc. decreases. Therefore, the ultrasonic irradiation temperature is set to the liquidus temperature or higher and within 100 ° C. from the liquidus temperature.
超音波照射時間は30秒以上にする。これにより、超音波照射により粗大な化合物の晶出を防止する効果があり、これより短いとTiB2の均一な分散化とAl3Tiなどの化合物の微細化の効果が発揮され難くなってしまうためである。
さらに、超音波照射後180秒以内に20℃／s以上の冷却速度で加圧鋳造を行う。超音波照射後180秒以内とするのは、分散させたTiB2が元の状態に戻り、粗大な化合物の微細化効果が消失してしまうのを防ぐためである。冷却速度は20℃／sより遅いと、晶出物が成長する時間があるため、晶出物の粗大化を招いてしまうためである。晶出物が粗大化するとそれを起点として破壊が起こり、機械的強度が低くなってしまう。
The ultrasonic irradiation time should be 30 seconds or longer. This has the effect of preventing crystallization of coarse compounds by ultrasonic irradiation, and if shorter than this, the effect of uniform dispersion of TiB 2 and the refinement of compounds such as Al 3 Ti will be difficult to be exhibited. Because.
Furthermore, pressure casting is performed at a cooling rate of 20 ° C./s or more within 180 seconds after ultrasonic irradiation. The reason why it is within 180 seconds after ultrasonic irradiation is to prevent the dispersed TiB 2 from returning to its original state and losing the refinement effect of the coarse compound. This is because if the cooling rate is lower than 20 ° C./s, there is a time for the crystallized product to grow, leading to coarsening of the crystallized product. When the crystallized material becomes coarse, it breaks from the starting point and the mechanical strength is lowered.
また、加圧鋳造として、ダイカスト法や半凝固ダイカスト法があるが、所定の位置で超音波照射することによって、180秒以内で鋳造をすることができる。180秒以内で鋳造を開始するための超音波照射位置として例えば溶解炉内，ラドル内，湯溜り内，スリーブ直上，スリーブ内などがあげられる。
これらの処理を行うことで、TiB2の凝集体が1mm3当たり5個以下、粗大な化合物の最大サイズが50μm以下、鋳巣の面積率が5％以下である剛性及び靭性に優れたアルミニウム合金を得ることができる。
In addition, as pressure casting, there are a die casting method and a semi-solid die casting method, and casting can be performed within 180 seconds by irradiating ultrasonic waves at a predetermined position. Ultrasonic irradiation positions for starting casting within 180 seconds include, for example, in the melting furnace, in the ladle, in the hot water pool, directly above the sleeve, and in the sleeve.
By performing these treatments, an aluminum alloy with excellent rigidity and toughness with 5 TiB 2 aggregates per mm 3 or less, a maximum size of coarse compounds of 50 μm or less, and an area ratio of the casting cavity of 5% or less Can be obtained.
さらに、本発明では、マトリックスはJIS規格のAC4C或いはAC4CHを基本とするものであるから、機械的強度改善を目的として時効硬化処理をすることができる。そのための溶体化処理及び時効硬化のための熱処理は、JIS規格のAC4C或いはAC4CHのそれと同様に実施すればよい。
すなわち、溶体化処理を500℃〜535℃で6〜8時間した後、100℃以下までを20℃／s以上の冷却速度で冷却し、その後時効効果のために熱処理を150℃〜300℃で1〜10時間行う。
Furthermore, in the present invention, since the matrix is based on JIS standard AC4C or AC4CH, it can be age-hardened for the purpose of improving mechanical strength. The heat treatment for solution treatment and age hardening for that purpose may be carried out in the same manner as that of JIS standard AC4C or AC4CH.
That is, after the solution treatment at 500 ° C. to 535 ° C. for 6 to 8 hours, the solution is cooled to 100 ° C. or less at a cooling rate of 20 ° C./s or more, and then heat treatment is performed at 150 ° C. to 300 ° C. for aging effect. Perform for 1-10 hours.
溶体化処理が500℃未満、または6時間未満であると溶体化が不完全であり、その後に時効硬化処理を行っても、機械的強度は改善されない。他方、溶体化処理は535℃以下、かつ8時間以内で十分であり、それを超えての溶体化処理は、コストの増大を招くほか、本発明においてはAl3Ti化合物の粗大化の要因ともなるため、好ましくない。
溶体化処理後は100℃以下までを20℃／s以上の冷却速度で冷却する。例えば直径30mmの球形の部材であれば、10dm3以上の容量の10℃〜50℃の水中に投入すれば、20℃／s以上の冷却速度を実現できる。もちろん100℃までを20℃／s以上の冷却速度で冷却できるのであれば、他の方法によることもできる。冷却速度が20℃／s未満であると、冷却中にMg2Siが析出したり、Al3Tiが粗大化したりすることがあるため、好ましくない。
When the solution treatment is less than 500 ° C. or less than 6 hours, the solution treatment is incomplete, and the mechanical strength is not improved even if the age hardening treatment is performed thereafter. On the other hand, the solution treatment is 535 ° C. or less and within 8 hours is sufficient, and the solution treatment beyond that causes an increase in cost, and in the present invention, it is a factor of coarsening of the Al 3 Ti compound. Therefore, it is not preferable.
After solution treatment, it is cooled to 100 ° C or lower at a cooling rate of 20 ° C / s or higher. For example, in the case of a spherical member with a diameter of 30 mm, a cooling rate of 20 ° C./s or more can be realized if it is poured into 10 ° C. to 50 ° C. water having a capacity of 10 dm 3 or more. Of course, other methods can be used as long as the temperature can be cooled to 100 ° C. at a cooling rate of 20 ° C./s or more. A cooling rate of less than 20 ° C./s is not preferable because Mg 2 Si may precipitate during cooling or Al 3 Ti may become coarse.
時効硬化のための熱処理が150℃未満、または1時間未満であると時効硬化が不十分であり、機械的強度が改善されない。他方、時効硬化のための熱処理は300℃以下、かつ10時間以内で十分であり、それを超えての溶体化処理は、コストの増大を招くことになるため、好ましくない。
このような時効硬化処理により、高い剛性を保ったまま、より一層の機械的強度の改善を図ることができるため、自動車用ナックルアームやホイール、内燃機関のシリンダーヘッドのほか、プラスチックの超音波加工用の振動子などの素材として、より好適な部材を得ることができる。
If the heat treatment for age hardening is less than 150 ° C. or less than 1 hour, age hardening is insufficient and the mechanical strength is not improved. On the other hand, heat treatment for age hardening is sufficient at 300 ° C. or less and within 10 hours, and solution treatment beyond this is not preferable because it leads to an increase in cost.
This age-hardening treatment can further improve mechanical strength while maintaining high rigidity. Therefore, in addition to automotive knuckle arms and wheels, internal combustion engine cylinder heads, and plastic ultrasonic processing. A more suitable member can be obtained as a material such as a vibrator.
〔実施例１〕
表１に実施例１として示した組成のアルミニウム合金1kgを溶解炉内に配置した坩堝内に用意した。合金の溶製には、純度99.9%のアルミニウム、Al‐25%Si、純度99.95%のマグネシウム、Al‐10%TiおよびAl‐4%Bの母合金を用いた。この溶湯にNb‐Mo合金製の超音波ホーンを予熱炉内で予熱した後、坩堝内のアルミニウム合金溶湯中にホーンを浸漬させて、超音波を650℃で300秒間照射した。このときの超音波振動の共振周波数は23kHz、音響出力を2kW、振幅（p‐p）を40μmに設定して行った。なお、この溶湯の液相線は613℃である。
[Example 1]
1 kg of an aluminum alloy having the composition shown in Table 1 as Example 1 was prepared in a crucible placed in a melting furnace. For the melting of the alloys, 99.9% pure aluminum, Al-25% Si, 99.95% pure magnesium, Al-10% Ti and Al-4% B master alloys were used. An ultrasonic horn made of Nb-Mo alloy was preheated in this molten metal in a preheating furnace, and then the horn was immersed in the molten aluminum alloy in the crucible and irradiated with ultrasonic waves at 650 ° C. for 300 seconds. At this time, the resonance frequency of the ultrasonic vibration was set to 23 kHz, the sound output was set to 2 kW, and the amplitude (pp) was set to 40 μm. In addition, the liquidus of this molten metal is 613 degreeC.
この溶湯をカップに移湯して、600℃まで冷却して半凝固材を作製し、超音波照射終了から120秒以内に20℃／s以上で加圧鋳造を行い、板状サンプルを作製した。この時の固相温度は577℃であった。
その後、溶体化処理500℃〜535℃で6〜8時間行った後、10℃の水中に急冷し時効効果のための熱処理を155℃で6時間行った。
続いて、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出した。さらにTiB2の凝集体の個数については、10mm2のアルミニウム表面を深さ方向に20μmずつ5回エッチングして、同一位置の10mm2についてそれぞれの深さにおけるTiB2の凝集体の個数を顕微鏡観察によって求め、粗大な化合物サイズ、鋳巣の面積率については画像解析を行って求めた。
This molten metal was transferred to a cup, cooled to 600 ° C to produce a semi-solid material, and subjected to pressure casting at a rate of 20 ° C / s or more within 120 seconds from the end of ultrasonic irradiation to produce a plate sample. . The solid phase temperature at this time was 577 ° C.
Thereafter, solution treatment was performed at 500 ° C. to 535 ° C. for 6 to 8 hours, followed by quenching in 10 ° C. water and heat treatment for aging effect at 155 ° C. for 6 hours.
Subsequently, as shown in Table 2, tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, and Young's modulus E were measured and calculated as room temperature tensile properties. Further, regarding the number of TiB 2 aggregates, the 10 mm 2 aluminum surface was etched 5 times by 20 μm in the depth direction, and the number of TiB 2 aggregates at each depth for 10 mm 2 at the same position was observed with a microscope. The coarse compound size and the cast hole area ratio were obtained by image analysis.
〔実施例２〜３〕
組成を表２のように変化させた以外は、実施例１と同様の方法で坩堝内に超音波照射を行い、半凝固ダイカスト鋳造、溶体化処理を行った。なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
[Examples 2-3]
Except for changing the composition as shown in Table 2, the crucible was irradiated with ultrasonic waves in the same manner as in Example 1 to perform semi-solid die casting and solution treatment. The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
〔実施例４〕
液相線以上で加圧鋳造を開始した以外は、実施例１と同一の組成、同一の条件で超音波照射を行い、溶体化処理を行った。なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
Example 4
Except for starting the pressure casting above the liquidus, ultrasonic treatment was performed under the same composition and the same conditions as in Example 1 to perform a solution treatment. The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
〔実施例５〕
溶体化処理の温度を変化させた以外は、実施例３と同一の組成、同一の条件で超音波照射を行い、半凝固ダイカスト鋳造を行った。なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
Example 5
Except for changing the temperature of the solution treatment, ultrasonic irradiation was performed under the same composition and the same conditions as in Example 3 to perform semi-solid die casting. The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
〔実施例６、７〕
組成を表２のように変化させた以外は、実施例１と同様の方法で坩堝内に超音波照射を行い、半凝固ダイカスト鋳造、溶体化処理を行った。なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
[Examples 6 and 7]
Except for changing the composition as shown in Table 2, the crucible was irradiated with ultrasonic waves in the same manner as in Example 1 to perform semi-solid die casting and solution treatment. The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
〔比較例１〜２〕
組成を表２のように変化させた以外は、実施例１と同様の方法で坩堝内に超音波照射を行い、半凝固ダイカスト鋳造、溶体化処理を行った。なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
[Comparative Examples 1-2]
Except for changing the composition as shown in Table 2, the crucible was irradiated with ultrasonic waves in the same manner as in Example 1 to perform semi-solid die casting and solution treatment. The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
〔比較例３〕
組成を表２に示す通り実施例３と同一にし、超音波処理の変わりに機械的撹拌を行った。機械的撹拌の条件としては、溶湯を液相線以上に保持しこの溶湯を回転翼サイズ40×50ｍｍ、回転数7回／ｓにて300秒間機械的に撹拌した。その後、実施例１と同様に半凝固材を作製し、撹拌終了から120秒以内に20℃／s以上で加圧鋳造を行い、板状サンプルを作製した。
なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
[Comparative Example 3]
The composition was the same as in Example 3 as shown in Table 2, and mechanical stirring was performed instead of ultrasonic treatment. As conditions for mechanical stirring, the molten metal was kept above the liquidus, and the molten metal was mechanically stirred for 300 seconds at a rotor blade size of 40 × 50 mm and a rotational speed of 7 times / s. Thereafter, a semi-solid material was prepared in the same manner as in Example 1, and pressure casting was performed at 20 ° C./s or more within 120 seconds from the end of stirring to prepare a plate sample.
The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
〔比較例４〕
組成を表２に示す通り実施例３と同一にし、実施例１と同様の方法で坩堝内に超音波照射を行い、冷却速度20℃／s以上にて重力鋳造を行った。その後実施例１と同一の条件で溶体化処理を行った。なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
[Comparative Example 4]
As shown in Table 2, the composition was the same as in Example 3, ultrasonic irradiation was performed in the crucible by the same method as in Example 1, and gravity casting was performed at a cooling rate of 20 ° C./s or higher. Thereafter, a solution treatment was performed under the same conditions as in Example 1. The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
〔比較例５〕
組成を表２のように変化させた以外は、実施例１と同様の方法で坩堝内に超音波照射を行い、半凝固ダイカスト鋳造、溶体化処理を行った。なお、液相線、固相線は実施例１と同様であった。そして、実施例１と同様に、表２に示すように室温引張特性として引張強度Rm、0.2％耐力Rp0.2、伸びA、ヤング率Eを測定、算出し、TiB2の凝集体の個数、粗大な化合物サイズ、鋳巣の面積率を求めた。
[Comparative Example 5]
Except for changing the composition as shown in Table 2, the crucible was irradiated with ultrasonic waves in the same manner as in Example 1 to perform semi-solid die casting and solution treatment. The liquidus and solidus were the same as in Example 1. Then, as in Example 1, as shown in Table 2, the tensile strength Rm, 0.2% proof stress Rp0.2, elongation A, Young's modulus E were measured and calculated as room temperature tensile properties, and the number of TiB 2 aggregates, The coarse compound size and the casting area ratio were determined.
実施例では、全てでTiB2の凝集体が1mm3に５個以下であり、粗大な晶出物の最大サイズが50μm以内であった。これにより、伸びAを2.0%以上、ヤング率Eを75GPa以上とすることができ、靭性及び剛性に優れたアルミニウム合金を作製できたことがわかる。
なお、実施例３によって製造されたアルミニウム合金のミクロ組織を図４に示す。この図からリング状のTiB2の凝集体は生成しておらず、TiB2は分散していることがわかる。
In the examples, the total number of aggregates of TiB 2 was 5 or less per 1 mm 3 , and the maximum size of coarse crystals was within 50 μm. As a result, it was found that the elongation A was 2.0% or more and the Young's modulus E was 75 GPa or more, and an aluminum alloy excellent in toughness and rigidity could be produced.
In addition, the microstructure of the aluminum alloy manufactured by Example 3 is shown in FIG. Aggregates of the ring-shaped TiB 2 from the figures are not generated, TiB 2 is seen to disperse.
比較例１については、伸びをはじめとするその他の特性は良好であったが、TiとBの含有量が低いため、充分な剛性を得ることができなかった。
比較例２については、TiとBの含有量が高く剛性は良好であるが、TiB2の凝集体が数多く生成してしまうため、伸びがかなり低くなってしまう。また、Ti添加量が多いため粗大な化合物が晶出する。さらに鋳巣の面積率も高かった。
In Comparative Example 1, the other characteristics including elongation were good, but sufficient rigidity could not be obtained because the contents of Ti and B were low.
In Comparative Example 2, the Ti and B contents are high and the rigidity is good. However, since many aggregates of TiB 2 are generated, the elongation is considerably low. Moreover, since the amount of Ti added is large, a coarse compound is crystallized. In addition, the area ratio of the cast hole was high.
比較例３については、実施例３と組成や工法、熱処理条件は同一であるが、超音波照射の代わりに機械的撹拌を行った。TiとBが適量添加されているため、剛性は良好であるが、機械的撹拌のみではTiB2の分散が足りず、伸びが低くなってしまった。また比較例３によって製造されたアルミニウム合金のミクロ組織を図５に示す。この図からもTiB2のリング状の凝集体やAl3Tiの粗大な化合物が多数生成していることがわかる。
比較例４については、TiとBが適量添加されているため、剛性は良好であり、Al3Tiも微細化したが、重力鋳造では鋳巣の面積率を抑えることができず、伸びも低かった。
比較例５については、実施例６と同様にMnとCrを加えており、剛性は良好であったが、MnおよびCrの添加量がそれぞれ４質量％と多く、破壊の起点となるAlMn系，AlMnSi系，AlCr系，AlCrSi系晶出物が晶出するため、伸びが低下してしまった。粗大な化合物（60μm）はAlMn系，AlMnSi系，AlCr系，AlCrSi系晶出物である。
For Comparative Example 3, the composition, construction method, and heat treatment conditions were the same as in Example 3, but mechanical stirring was performed instead of ultrasonic irradiation. Since Ti and B are added in appropriate amounts, the rigidity is good, but mechanical stirring alone does not provide sufficient dispersion of TiB 2 and elongation is low. Moreover, the microstructure of the aluminum alloy manufactured by the comparative example 3 is shown in FIG. This figure also shows that many TiB 2 ring-shaped aggregates and coarse Al 3 Ti compounds are formed.
In Comparative Example 4, since Ti and B were added in appropriate amounts, the rigidity was good and Al 3 Ti was also refined. However, the area ratio of the cast hole could not be suppressed by gravity casting, and the elongation was low. It was.
In Comparative Example 5, Mn and Cr were added in the same manner as in Example 6 and the rigidity was good. However, the amount of Mn and Cr added was as large as 4% by mass, respectively, and an AlMn system, which is the starting point of fracture, Since AlMnSi-based, AlCr-based, and AlCrSi-based crystallized crystals crystallize, the elongation decreased. Coarse compounds (60 μm) are AlMn-based, AlMnSi-based, AlCr-based, and AlCrSi-based crystals.
本発明によれば、剛性が高く、アルミニウム合金との濡れ性にも優れるTiB2を分散材として複合化させるにあたって分散材をアルミニウム合金の部材全体にわたって均一に分散させるとともに、Al3Ti化合物などの粗大防止することにより、剛性が高く、部材全体にわたって特性の均一なアルミニウム合金及びその製造方法が提供される。 According to the present invention, when compounding TiB 2 having high rigidity and excellent wettability with an aluminum alloy as a dispersion material, the dispersion material is uniformly dispersed throughout the entire member of the aluminum alloy, and an Al 3 Ti compound or the like is used. By preventing coarseness, an aluminum alloy having high rigidity and uniform characteristics over the entire member and a method for producing the same are provided.
１ 超音波ジェネレータ
２ 振動子
３ ホーン
４ ネジ方式接続
５ 制御ユニット
DESCRIPTION OF SYMBOLS 1 Ultrasonic generator 2 Vibrator 3 Horn 4 Screw system connection 5 Control unit
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| JPH03249148A (en) * | 1990-02-27 | 1991-11-07 | Showa Alum Corp | Low thermal expansion aluminum alloy excellent in strength and ductility |
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